The invention concerns a horizontal boring apparatus including a travelling framework or boring carriage, onto which is arranged a boring ramp for guiding the boring rod, a rod magazine for receiving individual boring rod sections, a drive unit for the travelling framework and the boring rod, and an operator station, and a mixing apparatus for the preparation of flushing fluid with a mixing unit including a mixing pump.
Horizontal boring apparatuses of the previously described type are known for the emplacement of pipes. With these a flushing fluid is used, which for example consists of a water-bentonite mixture, and is created in the mixing apparatus and then pumped into the borehole by means of a high-pressure pump.
In today""s controllable horizontal boring apparatuses of the aforementioned type one differentiates essentially two forms of the apparatus. In the first form, the mixing apparatus is separated from the travelling framework and is arranged, for example on a truck. It includes a flushing fluid tank having a capacity of between 1,000 to 6,000 liters. A disadvantage of this solution is that the mixing apparatus must be provided with its own drive motor. Usually such a drive motor is a gasoline or diesel motor of 20 to 30 horsepower. Moreover, before the beginning of a boring procedure the mixing apparatus must be connected through a liquid conducting hose of sufficiently large size to the boring apparatus, which for each boring procedure requires additional set-up time.
In a second form of the apparatus, the complete mixing apparatus including the flushing fluid tank, is arranged on the travelling framework. This solution has the advantage that almost no set-up time is required for starting operation. But the capacity of the flushing fluid tank because of space and weight considerations is necessarily limited. This can especially lead to problems if long borings need to be undertaken and if the boring place is situated a great distance from a hydrant, or if on other grounds a sufficient feed of flushing fluid is difficult to maintain. Moreover, because of the space required for the flushing fluid tank only short boring rod sections can be used. Therefore, more time is required for boring rod section changes.
The invention has as its object the provision of a horizontal boring apparatus of the aforementioned type which, on one hand, requires little set up time for starting operation, and which on the other hand, offers the possibility of being able to prepare a sufficient amount of flushing fluid.
The above object is solved in accordance with the invention in that the mixing unit is arranged on the travelling framework and has an inlet port releasably connectable with a liquid source and at least one outlet port releasably connectable with a flushing fluid receiver.
Whereas in previous solutions, the mixing unit and the flushing fluid tank are always fixedly connected with one another into one unit independently of whether the mixing apparatus is arranged on the travelling framework or to one side of the travelling framework, in the arrangement of the invention, the mixing unit is an individual unit separate from the flushing fluid tank. This separation of the mixing apparatus from the flushing fluid tank offers an abundance of possibilities and a high flexibility in the preparation of the required amount of flushing fluid, and indeed both in the case where the mixing apparatus is mounted on the travelling framework and in the case where the mixing apparatus stands separately, even though in the following essentially only the first case is discussed.
First of all the arrangement of the mixing apparatus on the travelling framework offers the possibility of coupling the mixing pump with the framework drive apparatus. A separate motor for the mixing pump can therefore be avoided.
Moreover, since the mixing apparatus is not necessarily connected with the flushing fluid tank there exists the further possibility of connecting the inlet port of the mixing apparatus directly to an external water source, for example a hydrant. The inlet port however also, as previously, can be connected with a flushing fluid tank, so that a releasable connection gives the possibility of connecting to a substitute tank when the first tank is empty or to switch to a substitute tank, with the first tank then in the intermediate time being again filled with water.
Likewise, the outlet port of the mixing apparatus can be directly connected with a high pressure pump for the delivery of the flushing fluid to the bore hole (pass through mixer without flushing fluid tank) or with a flushing fluid tank. In both cases, the mixing of the desired material, for example bentonite, to the water can be accomplished with the help of an injector, which is arranged downstream of the pressure side of the mixing pump, with the suction port of the injector being connectable with a source of the material to be mixed with the water.
In another embodiment the mixing apparatus has a first outlet port which is connectable with a flushing fluid tank, and a second outlet port connected with a high pressure pump for delivering the flushing fluid to the bore hole, with the pressure side of the mixing pump being selectably connectable with one of the two outlet ports. The mixing can again take place as previously described with the help of an injector arranged between the pressure side of the mixing pump and the first outlet port or between these and the flushing fluid tank. Preferably, the injector is arranged directly at the flushing fluid tank. If the flushing fluid tank, for example, is on the vehicle which also transports the material, for example Bentonite, to be mixed with the water, the material need not be transported to the boring carriage. Another possibility exists in that water and the material to be added to it are directly introduced to the flushing fluid tank and both substances are recirculated with the mixing pump until the desired mixture is achieved. Whereafter the mixing pump delivers the mixture under moderate pressure to the high-pressure pump through the second outlet port.
Advantageously, a flushing fluid filter is arranged in advance of the high-pressure pump in order to strain large pieces from the mixture and to thereby keep these large pieces from reaching the high-pressure pump.
Further features and advantages of the invention will be apparent from the following description, which in connection with the accompanying drawings explains the invention by way of exemplary embodiments.